slideme works, so does andappstore. However you can't buy any apps because the Egg doesn't expose the device ID. I haven't tried any other app stores. Pretty much any app that doesn't use one of:
1)GPS
2)Camera
3)Telephone
works, with some exceptions of course.

If you get the .apk files for an app you can install them without using an app store. Also paid for apps work this way as well(BeyondPod offers a paypal purchase method and they send you the unlock .apk that you can then use).

No flash unfortunately. And the Egg will only have Flash lite and from what I'm told that means no youtube.

$300? No. It's very unusable as a device right now. Unless you are interested in Plaszma as a development environment I would suggest staying away from the Egg. And if you are interested in Plaszma as a development environment I would suggest you look elsewhere for a development environment.

We are talking Android right? You can download some things from the browser. However you need an SD card for the current Android release. You have no access to the internal storage in Android(not for "drag and drop", apps can use it to install on but you can't put anything there). For installing apps I used the command line tools adb, adb install appname.apk and that would install it. You could also use SD card installer apps that install apps from the SD card(SlideME guys made one), so you could drag and drop the apk files to the sd card and use that app to install them.

Android isn't very good for listening to music though. It's hard to change the volume and all the buttons cause distortion in the music.

In Android? It's ok I guess, but like I said there is a lot of interference when any button or or the screen is touched. Also if you are playing music while it is plugged in the sound is completely destroyed.

These things don't happen in Plaszma. But there is no EQ and X-Fi audio processing isn't implemented yet. I'm not really an audiophile or anything but I kinda like the sound from my Fuze more. Though I haven't really listened to it a whole lot, it's not something you can use on a day to day basis as a player.

If you want it to listen to music just put it out of your head for now. The only thing it is really good for is testing Plaszma apps, and even then it's not really stable enough for serious development.